KR101772419B1 - Electrode for Secondary Battery having high adhensive strength with separator - Google Patents

Abstract

The present invention relates to an electrode for a secondary battery, in which an electrode active material, a binder and, optionally, an electrode material mixture containing a conductive material is coated, and a binder layer for improving adhesion to the separator is formed on one surface or both surfaces of the electrode. And the binder layer is coated on one or both surfaces of the electrode in an area of 20% to 50% of the area of one surface of the electrode.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a secondary battery having a high adhesive strength and a separator,

The present invention relates to a separator and an electrode for a secondary battery having improved adhesion.

BACKGROUND ART [0002] In recent years, rechargeable secondary batteries have been extensively used as an energy source or an auxiliary power device for wireless mobile devices. In addition, the secondary battery is an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (HEV), and the like, which are proposed as solutions for air pollution of existing gasoline vehicles and diesel vehicles using fossil fuels (Plug-In HEV) and the like.

Such a secondary battery is manufactured such that the electrode assembly is embedded in the battery case together with the electrolyte solution. The electrode assembly is a structure made up of an anode, a cathode, and a separator. The electrode assembly is classified into a stack, a folding, and a stack-folding type according to a manufacturing method.

The positive electrode and the negative electrode of the electrode assembly are mixed with an electrode material organic solvent containing an electrode active material on one surface or both surfaces of a metal current collector, slurrying the coated material, applying the slurry, and drying the coated material.

In general, the electrode assembly composed of the anode / separator / cathode may have a laminated structure, but a plurality of electrodes (anode and cathode) may be laminated with a separator interposed therebetween and then heated / . In this case, the bonding of the electrode and the separator is achieved by heating / pressing the electrode and the adhesive layer formed on the separator in a face-to-face relationship. Therefore, the separator is generally coated with a binder material to improve the adhesion with the electrode.

However, in such a conventional method, since the binder layer is formed using polymer phase separation on the surface of the separation membrane, it is difficult to keep the separation of the separation membrane, so that the adhesion between the separation membrane and the electrode necessarily decreases.

In addition, when the binder layer coated with such a binder material is used in an electrochemical cell such as a battery, if the binder powder has weak adhesion between the separator and the electrode, the binder is removed from the separator base material in the electrolyte injection and degassing process, So that a flow phenomenon may occur. As a result, the appearance and performance of the battery cell may be deteriorated.

Therefore, there is a high need for an electrode having a structure capable of maintaining an adhesive force between the electrode and the separator.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

The inventors of the present application have conducted intensive research and various experiments and confirmed that it is possible to achieve a desired effect by using an electrode coated with a binder layer for improving adhesion to a separator, I have come to completion.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, an electrode for a secondary battery includes an electrode active material, a binder, and optionally an electrode material mixture containing a conductive material coated thereon. The binder layer may be coated on one surface or both surfaces of the electrode or separator in an area of 20% to 50% of the surface area of the electrode or separator.

That is, in the electrode for a secondary battery according to the present invention, the surface of the electrode or the separation membrane is coated with a binder layer capable of improving the mutual adhesion force, so that the thinning of the binder layer is maintained, It can be kept intact.

Generally, as the content of the adhesive material such as a binder and the contact area increase, the resistance increases. In the present invention, the binder layer does not cover the entire surface of the electrode or the separator but has a surface area of 20% To 50%, it is possible to increase the mutual adhesion between the electrode and the separator in a large area without increasing the resistance.

In one specific example, the binder layer may comprise an adhesive material.

Wherein the adhesive material is selected from the group consisting of polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, And may be at least one selected from the group consisting of polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butylene rubber, and fluorine rubber.

The thickness of the binder layer may be 0.1 micrometer to 10 micrometer.

When the thickness of the binder layer is 0.1 micrometer or less, the effect of improving the adhesion can not be expected. When the thickness of the binder layer is 50 micrometers or more, the total area of the binder layer is large.

When the adhesive material is contained in the binder layer at a weight ratio of less than 30%, the adhesive strength may be lowered. If the adhesive material is contained in excess of 70%, the resistance is greatly increased.

In one specific example, the binder layer may consist of two or more positive patterns protruding from the surface of the electrode or separator.

Such a pattern may be formed in various shapes, for example, a structure in which unit pieces having a certain area are arranged, or a structure in which unit lines are arranged to form a specific shape.

As one example of such a relief pattern, the relief pattern may be a planar polygonal unit or a circular unit, and the unit may have an area of 1% to 10% of an area of one surface of the electrode or the separator.

When the area is less than 1%, it is difficult to coat the unit body on the surface of the electrode or the separator, and it is difficult to expect the adhesive force along the binder layer due to the narrow area of the unit body. If the area exceeds 10%, the contact area between the electrode or the separator and the unit body is widened, and the contact resistance may increase, which is not preferable.

The unit body may be distributed on the surface of the electrode or separator except for the area of 1% to 40% of the total area of the electrode on one side of the electrode or separator. That is, when the unit bodies are formed on the surface of the electrode, the electrode terminals may be disposed at a certain distance from the end portions of the electrodes where the electrode terminals may be formed.

Such a structure can minimize the increase in resistance at the end portions by not arranging the binder layer at a portion adjacent to the end portion of the electrode where charges are concentrated.

In addition, the unit pieces may be regularly arranged on the surface of the electrode or the separator with a spacing of 10% to 500% of the widest width among the widths thereof.

That is, each of the unit bodies is arranged in a state of being spaced apart from each other by a predetermined distance, and the spacing distance may be constant. When the spacing distance is less than 10%, it is difficult to form the unit body on the electrode or the separator because the unit bodies are arranged in an excessively close state. When the spacing is more than 500% Which is undesirable because the number of units capable of being reduced.

As another example of the relief pattern, the relief patterns may be a structure in which two or more relief lines form a pattern in a mutually connected manner.

The embossing lines may be curved or straight in a plane, and the two or more embossing lines may be interconnected to form a pattern of various shapes.

For example, the pattern may be, but is not limited to, a planar shape, a polygonal shape in which three or more relief lines are connected to each other, or a curved relief line.

The width of the relief lines may be greater than or equal to 5 microns and less than or equal to 10 millimeters, and the length of the relief lines may be between 5 times and 1000 times greater than the width.

When the width of the embossed lines is less than 0.1 millimeter, the area of the embossed lines is small, so that the adhesion between the electrodes and the separator is not easy. When the width exceeds 10 millimeters, the surface area of the pattern formed by the embossed lines becomes wider, .

The present invention also provides a method for manufacturing the electrode for a secondary battery. Specifically, the method comprises:

a) forming a binder layer on one side or both sides of the electrode or separator;

b) applying a slurry containing an electrode mixture to the surface of the electrode or separator having the binder layer formed thereon;

c) drying and rolling the electrode mixture slurry applied to the electrodes or separator;

d) a step of bonding the electrode and the separator to each other;

. ≪ / RTI >

Here, the step a) is not limited as long as it is a step of forming a fine pattern, but it may include the following pattern forming method in detail.

As one example, the step a) includes the steps of: preparing a master mold in which a relief pattern corresponding to the shape of the binder layer is stamped;

Applying an adhesive material to the relief surface of the master mold by contact with a paste for forming a binder layer;

Drying the paste to evaporate the solvent;

Replicating the paste of the surface of the embossed surface in the master mold to the electrode or the surface of the separating membrane; And

Drying the transferred face to form a binder layer;

. ≪ / RTI >

The pattern forming method is advantageous in that the pattern forming process is simple and the process can be automated.

As another example, the step a) includes the steps of: preparing a silicon mold having engraved pattern corresponding to the shape of the binder layer;

Applying a paste for forming a binder layer containing an adhesive material on the entire surface of the master mold surface of the plate type by contact;

Drying the paste to evaporate the solvent;

Contacting the dried master mold with the silicon mold to transfer the paste to the embossed angle of the silicon mold and holding the paste of the master mold at the position corresponding to the engraved angle of the silicon mold on the surface of the master mold;

Removing the master mold from the silicon mold, and then replicating the paste remaining on the master mold to the electrode or separator surface;

. ≪ / RTI >

Such a pattern forming method has an advantage that a very precise and precise pattern can be formed.

In these methods, the mold may be a highly flexible PDMS (Polydimethylsiloxane) mold.

In addition, the solvent may be an alkanethiol to form self-assembled monolayers.

The present invention also provides a secondary battery comprising the secondary battery electrode, wherein the secondary battery may be a lithium ion battery or a lithium polymer battery.

The present invention also provides a battery module including the secondary battery as one or more unit cells and a device using the battery module as a power source.

The device may be one selected from a cell phone, a portable computer, a smart phone, a smart pad, a tablet PC, a netbook, a LEV (Light Electronic Vehicle), an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, . The structure of these devices and their fabrication methods are well known in the art, and a detailed description thereof will be omitted herein.

As described above, the electrode for a secondary battery according to the present invention has a binder layer coated on the surface of the electrode, which can improve the adhesion to the separator, so that the thinning of the binder layer is maintained, It can be kept intact.

1 is a schematic view of an electrode according to the present invention;
2 is a perspective view of the electrode shown in Fig. 1;
3 is a schematic view of an electrode in which a binder layer according to one embodiment is formed;
Figure 4 is an enlarged view of the binder layer of the relief pattern of Figure 3;
5 is a schematic view illustrating a binder layer forming process according to an embodiment of the present invention;
6 is a schematic view illustrating a process of forming a binder layer according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited by the scope of the present invention.

FIG. 1 schematically shows an electrode according to the present invention, and FIG. 2 is a perspective view of the electrode shown in FIG.

Referring to these drawings, the electrode 100 includes a current collector 110 having an electrode terminal 111 formed at one end thereof, a binder layer 130 coated on a part of the surface of the electrode 100, And an electrode material mixture 120 coated on the surface and the binder layer 130. Here, since the electrode layer 100 is coated with the binder layer 130, the binder layer 130 including the adhesive material improves the adhesion between the electrode 100 and the separation layer 150.

The binder layer 130 is regularly arranged on one surface of the electrode 100 such that six unit pieces are spaced apart from each other and spaced apart from each end of the electrode 100 by a certain distance.

The binder layer 130 is adhered not only to the surface of the electrode 100 but also to a portion where the binder layer 130 protrudes from the electrode 100 by a thickness of the electrode mixture 120, And the adhesive component included in the binder layer 130 can firmly hold the electrode mixture 120 on the electrode 100. In addition,

FIG. 3 shows an electrode coated with a binder layer of another form in FIG. 2, and FIG. 4 is an enlarged schematic view of the binder layer.

Referring to these drawings, a binder layer 160 in the form of a relief pattern in which relief lines 161 are coupled to each other is formed on the surface of the electrode 100.

These binder layers 160 form a hexagonal pattern in which the six relief lines 161 are connected to each other and form an inner space 170 therebetween except for each of the relief lines 161. [

Wherein the outer surface of the relief line 161 has a length L that is approximately ten times the width W and the electrode combination is applied on the outer surface of the relief line 161 formed by the width W and length L . Although not shown here, an electrode combination may be applied to the internal space 170 formed between the raised lines 161 as well.

5, a binder layer forming process according to an embodiment of the present invention is schematically illustrated.

Referring to Fig. 5, in step (a), a master mold 200 on which a relief pattern 210 corresponding to the shape of the binder layer is stamped is prepared.

In step (b), the binder layer forming paste 220 is applied to the embossed surface 210 of the master mold 200 by contact, and then the paste 220 is dried, A desired binder layer forming paste 221 is formed on the embossed surface 210 of the substrate 200. Then, the paste 211 of the relief surface 210 is replicated on the surface of the electrode 100 in the master mold 220 to form the binder layer 130 on the surface of the electrode 100.

Meanwhile, FIG. 6 schematically shows a binder layer forming process according to another embodiment.

Referring to FIG. 6, in step (a), a paste for forming a binder layer adhesive portion 320 is applied over the entire surface of the master mold 300 of a flat plate shape. Thereafter, as in step (b), the paste 320 is dried to form a binder layer forming paste 321 evaporating the solvent on the entire surface of the master mold 300.

In step (c), the master mold 300 is brought into contact with the silicon mold 330 on which the engraved pattern corresponding to the shape of the binder layer is stamped. At this time, as in step (d), the paste 332 of the master mold 300 is transferred to the embossing of the silicon mold 300, and the paste 332 of the master mold 300 at the position corresponding to the engraved angle of the silicon mold 330 331 are held on the surface of the master mold 300.

Thereafter, the master mold 300 is removed from the silicon mold 330 in step (e), and the paste 331 remaining in the master mold 300 is replicated to the surface of the electrode 400, an electrode 400 having a binder layer 430 formed on its surface is manufactured as shown in FIG.

In the above description of the present invention, only a structure in which a binder layer is formed on the surface of the electrode is shown, but the present invention is not limited thereto, and a binder layer may be formed on the surface of the separation layer.

It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (25)

delete delete delete delete delete delete delete delete delete delete delete delete delete A method of manufacturing an electrode for a secondary battery,
a) forming a binder layer on one side or both sides of the separation membrane;
b) applying a slurry containing an electrode mixture onto the surface of the separation membrane having the binder layer formed thereon;
c) drying and rolling the slurry for the electrode material mixture applied to the separation membrane to bond the separation membrane and the slurry together;
/ RTI >
The process a) includes the steps of: preparing a master mold in which a relief pattern corresponding to the shape of the binder layer is stamped;
Applying a paste for forming a binder layer containing an adhesive material on the relief surface of the master mold by contact;
Drying the paste to evaporate the solvent;
Replicating the paste of the surface of the embossed surface in the master mold to the electrode or the surface of the separating membrane; And
Drying the transferred face to form a binder layer;
/ RTI >
Wherein the binder layer is coated on one surface or both surfaces of the electrode or separation membrane in an area of 20% to 50% of an area of one surface of the electrode or separation membrane. delete A method of manufacturing an electrode for a secondary battery,
a) forming a binder layer on one side or both sides of the separation membrane;
b) applying a slurry containing an electrode mixture onto the surface of the separation membrane having the binder layer formed thereon;
c) drying and rolling the slurry for the electrode material mixture applied to the separation membrane to bond the separation membrane and the slurry together;
/ RTI >
The process a) includes the steps of: preparing a silicon mold having an engraved pattern corresponding to the shape of the binder layer;
Applying a paste for forming a binder layer containing an adhesive material on the entire surface of the master mold surface of the plate type by contact;
Drying the paste to evaporate the solvent;
Contacting the dried master mold with the silicon mold to transfer the paste to the embossed angle of the silicon mold and holding the paste of the master mold at the position corresponding to the engraved angle of the silicon mold on the surface of the master mold;
Removing the master mold from the silicon mold, and then replicating the paste remaining on the master mold to the electrode or separator surface;
/ RTI >
Wherein the binder layer is coated on one surface or both surfaces of the electrode or separation membrane in an area of 20% to 50% of an area of one surface of the electrode or separation membrane. 17. The method of claim 14 or 16, wherein the mold is a PDMS (Polydimethylsiloxane) mold. 17. The method of claim 14 or 16, wherein the solvent is an alkanethiol to form self-assembled monolayers. delete delete delete delete A method of manufacturing an electrode for a secondary battery,
a) forming a binder layer on one side or both sides of the separation membrane;
b) applying a slurry containing an electrode mixture onto the surface of the separation membrane having the binder layer formed thereon;
c) drying and rolling the slurry for the electrode material mixture applied to the separation membrane to bond the separation membrane and the slurry together;
/ RTI >
The process a) includes the steps of: preparing a master mold in which a relief pattern corresponding to the shape of the binder layer is stamped;
Applying a paste for forming a binder layer containing an adhesive material on the relief surface of the master mold by contact;
Drying the paste to evaporate the solvent;
Replicating the paste of the surface of the embossed surface in the master mold to the electrode or the surface of the separating membrane; And
Drying the transferred face to form a binder layer;
/ RTI >
The binder layer is coated on one surface or both surfaces of the electrode or separation membrane in an area of 20% to 50% of the area of one surface of the electrode or separation membrane,
The binder layer comprises two or more relief patterns protruding from the surface of the electrode or separation membrane
Wherein the relief pattern is a polygonal unit body or a circular unit body in plan view,
Wherein the unit body is distributed on the surfaces of the electrodes or the separator except for an area of 1% to 40% of the total area of the electrode on one side of the electrode or the separator. A method of manufacturing an electrode for a secondary battery,
a) forming a binder layer on one side or both sides of the separation membrane;
b) applying a slurry containing an electrode mixture onto the surface of the separation membrane having the binder layer formed thereon;
c) drying and rolling the slurry for the electrode material mixture applied to the separation membrane to bond the separation membrane and the slurry together;
/ RTI >
The process a) includes the steps of: preparing a master mold in which a relief pattern corresponding to the shape of the binder layer is stamped;
Applying a paste for forming a binder layer containing an adhesive material on the relief surface of the master mold by contact;
Drying the paste to evaporate the solvent;
Replicating the paste of the surface of the embossed surface in the master mold to the electrode or the surface of the separating membrane; And
Drying the transferred face to form a binder layer;
/ RTI >
The binder layer is coated on one surface or both surfaces of the electrode or separation membrane in an area of 20% to 50% of the area of one surface of the electrode or separation membrane,
Wherein the binder layer comprises two or more positive patterns protruding from the surface of the electrode or separation membrane,
Wherein the relief pattern is a polygonal unit body or a circular unit body in plan view,
Wherein the unit pieces are regularly arranged on the surface of the electrode or the separator with an interval of 10% to 500% with respect to the widest width among the widths thereof. A method of manufacturing an electrode for a secondary battery,
a) forming a binder layer on one side or both sides of the separation membrane;
b) applying a slurry containing an electrode mixture onto the surface of the separation membrane having the binder layer formed thereon;
c) drying and rolling the slurry for the electrode material mixture applied to the separation membrane to bond the separation membrane and the slurry together;
/ RTI >
The process a) includes the steps of: preparing a master mold in which a relief pattern corresponding to the shape of the binder layer is stamped;
Applying a paste for forming a binder layer containing an adhesive material on the relief surface of the master mold by contact;
Drying the paste to evaporate the solvent;
Replicating the paste of the surface of the embossed surface in the master mold to the electrode or the surface of the separating membrane; And
Drying the transferred face to form a binder layer;
/ RTI >
The binder layer is coated on one surface or both surfaces of the electrode or separation membrane in an area of 20% to 50% of the area of one surface of the electrode or separation membrane,
Wherein the binder layer comprises two or more positive patterns protruding from the surface of the electrode or separation membrane,
Wherein the binder layer comprises an adhesive material.

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